In contrast with the pattern presented in ovarian and lung cancer, FRα is highly abundant in the healthy kidney parenchyma (up to 100% expression on the apical surface of the proximal tubules, providing physiologic folate reabsorption) [16] but less expressed within renal tumors [17,38], which appear dark (10–30% staining), while the surrounding normal tissue is brightly fluorescent [18]. This evidence concerns the gene FOLR1 and lung carcinoma.